Ignition system for airplane engines and the like



L. H. SCOTT June 16, 1942.

IGNITION SYSTEM Filed April 2, 1941 2 Sheets-Sheet 1 June 16, 1942.

IGNITION SYSTEM FOR AIRPLANB ENGINES AND THE LIKE Filed April 2, 1941 2 Sheets-Sheet 2 j Byy VINVENTS& 77010477 MM%/hi ATTORNE L. H. sco'r'r 2,286,233 V Patented June 16, 1942 UNITED ;STATES PATENT OFFlCE %286.233 IGNITION SYSTEM FORAIRPLANE ENGINES ANDTHE LIKE Application Aprilz. 194 1, Serial No. 3s6-,42z

16 Claims.

This invention relates to ignition systems for airplane motors or engines, and particularly to ignition systems provided with supercharging means, that is, means tor supplying air and main taining desired pressure thereot` adapting the 5 system fo: so-called high-altitude flying.

The invention has for its object the provision of a unitary ignition system for airplane motors which includes a supercharging system. for filling both the source of high tension curo rent and the harness with air under pressure.

More specifically, an object is to provide an ignition system for a multi-cylindered airplane engine which isflred from a single sourceof' high tension E. M. F., and incorporates means ,for circulating air under pressure through the source of current and ventilating the same, to-

p gether with a ventilated harness that is also filled a casing which is substantially airtight and has separate compartments with air circulating connections whereby improved ventilation is had.

Still another object is to provide a unitary ignition system having means for supercharging, in which all parts are balanced and matched.

Other objects of the invention will in part be obvious and will ;in part appear h`ereinafter.

The invention accordingly comprises the features of construction, combination'- of elements, and arrangement of parts, which will be exemplifled in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drawings, in which: l

Fig. 1 is a fragmentary view showing, mainly in elevation, an ignition Systemet the present invention which has a magneto -as the current source;

Fig. 2 is a view, partly in section and partly in elevation, showing details of the magneto emv ployed in the ignition system o! mg. 1;`

Fig. 3 is another view, partly in section and partly in elevation, showing a detail in the harness here employed; and

Fig. 4 is a view showing a modification; in which a battery is thesource of current.

Referring now to the drawings, and particularly to Fig. 1, an aii-plane engine E of the internal combustion type is shown by way of example. The engine isfired electrically and to this end has a plurality of spark plugs o, one for each cylinder if it has a single ignition, a pair being used for dual ignition. The plugs III are supplied with high tension electric current through harness II, from a suitable source 20, such as a magneto, preferably one supplying eiective fuel firing high tension current which may be largely unidirectional, as taught in U. S. Patent No. 2,015,091, issued in the name of M. E. Spohn on September 24, 1935.

The harness H comprises a plurality of conductors |2 leading from terminal connectors of a chamber C and are part of a distrlbutor housed 'in a chamber B (see Fig. 2) of an encasedmagsuch cable is disposed in slightly spaced relation` on the interior of a hollow metal, substantially airtight sheath !4 that is preferably flexible, and has an 'air-bleeding terminal [5 through which a terminal portion z' of conductor l2 is passed in an insulating manner in order that it may be e conductively connected to a spark plug n, as shown in Fig. 3. The terminal portion !5 oi' the sheath M is preferably detachable and is provided with one or more air-bleeding perforations as shown at IS. i

Each sheath M of the hamess ll is led in an airtight manner from a suitable opening invan air manifold |8 that is closed at one end and houses the cables leading from compartm'ent C of the magneto 20; air ma'nifold lil having a connection 19 that communicates with and may be integral with the casing portion housing the C- compartment ot magneto 20 (a second connection IS' being shown and used when dual ignition is employed).

The magneto here shown at 20 is that of my copending application, Serial No. 374324, filed January 14, 1941, and comprises a plurality of' functioning unit components of a magneto-electric machine, each housed in a substantially airtight compartment of a casing that is made as a substantially imperforate structure and adapted to be filled with air under pressure. In the arrangement shown, it is desired that the magneto be driven at one-half engine speed. This ratio may be had by means of a cam shaft in the engine, a gearing incorporated in the engine, or a suitable speed nging earing in the magneto, as desired.

Associated withthe same drivng connections is a. pump 30, which is adapted to pump a fluid dielectric and may be of any suitable variety, for example, a rotary pump with reciprocating vanes. such pump in order to pump air -has an inlet from the atmosphere, preferably provided with an air filter 3f, and an outlet here shown connected to a conduit 32 by which air under pressure is supplied at 22 to compartment A of the magneto. In compartnent 'A iswdis ing material; and that this partition wall serves as a distributor head in which are anchored terminal mountings whereby the conducting cables in chamber C including those leading to thespark plugs; such as conductors !2 encased in insulating envelopes [3, are brought into conducting relation with the rotary distributing plate 21 in chamber B. The mechanism structure is more completely described in the above identified application Serial No. 374324. However, since such details relate to subject-matter 'not herein claimed their reiteration herein is deemed unessential. For ready reference the partition wall between chambers B and C which prevents gases from passing from one to 'the other is referenced llll. As'shown this wall is a substantially fiat plate of substantially uniform thickness having the opposed faces thereof disposed in substantally parallel planes and as is obvious may be formed or cut from sheet insulating material. Each cable |2 l3 termi-'- nates at the plate I, serving as a distributor head, in a suitable terminal mounting as shown, each terminal mounting including a stationa'y electrode 12 mounted in a suitable busbing 80.

A high tension current supply cable 256 termi-' nates at'the plate III in a suitable transfer;

terminal 66 in a bushing 61. The rotating distributor plate 21 of insulating material carries an electrode 65 which is charged from the windings ofthe coil 25 through cable 258 by means of cooperation ofterminal GG and a centrally located contact il in the rotating plate 21. The contact SI is connected to the electrode 65 by means of an embedded conductor 54 as shown.

The air pressure in compartment A is preferably limited in value. To this end, the 'magneto casing has disposed in its wall at a desired point a safety valve 2l, or other suitable device. From compartment A the air or other fluid dielectric passes in pal-allal paths to compartments B and C. Accordingly. a passage 33 is provided in the separating wallbetween compartments A and B. The parallel path is through a conduit 3.4` formed on the outer wall of compartment B to convey conductor 256 from compartment A to compartment C. About the cable in conduit 34 is a suflicient clearance to permit the desired entrance of air under pressure at 35 into compa'rhnent C. The air in this letter compartment passes out through the connection |9 intothe manifold |8. The compartment B is provided with one or -more vents 36, which are preferably screened, for bleeding the air therein to the atmosphere. V V

Inthe manifold !8, the air under pressure is seen `to pass into'the harness II by dividing itself 'into a plurality of small streams, each entering the clearance space in a sheath !4 surrounding the cable therein. The air in such clearance spaces is` seen to flow to the ends and then through the openings I 6, in terminal portions 15, to the atmosphere.

In operation, when the magneto 20 is being driven by the engine E, the pump 30 is also being driven, and air drawn from the atmosphere through the inlet 3! is compressed and dis- 'charged under pressure through conduit 32 into the casing of the magneto at 22, i. e., into compartment A of the magneto casing. The presence of this air under pressure is seen to provide a fluid delectric of relatively high dielectrio strength about the windings; this is especially desired at high altitudes or in rarefied atmospheres.

During operation, the air from compartment A passes by way of opening 33 into compartment B. simultaneosly air is passed by Conduit 34 and opening 35 into compartment C. Any ozone,

or .other Corrosive by-product formed by the sparks in compartment B, is here fiushed out with the air vented .to the atmosphere through the vent or vents at 36. I

The air which enters compartment C passes through connection |9 alongside of the cables therein, and thenceto manifold l8, the air thus entering manifold I 8 then passing into the harness sheathing, and thence to the atmosphere through openings' s. such air for the harness is seen againto provide a fluid dielectric about the cables leading to the spark plugs and to the spark'plug terminals, and assists in insulating the same from the sheaths |4 and insures generally the proper performance of the ignition system.

The present invention is seen to provide a unitary ignition system in which all of the parts may be made to have a balanced perforance;

'the air passed into the system maintaining at all times a proper 'fluid dielectric about the high tension current carrying parts.

While the ignition system above described employs a magneto, as its source of E. M. F., the invention is not so' limited, as a battery having a make-and-break device and distributor of the type commonly used in automotive practice may also be used as a modified form of the invention. A modification using such source is shown in Fig'4, the coil comprising one unit of the source, the breaker and distributor another. By the present invention, the source has a casing pro- 'vided with separate or segregating Compartments, one for each of said units.

In the modification shown in Fig. 4, the casing having compartments is shown at 40; the compartments being denoted 4l, 42, and 43, respectively. In compartment 'is a coil 45, while compartment 42 contains a breaker 46 and a distributor 41. Compartment 44 contains the usual battery and as shown is connected to compartment 4|by a suitable ductors between the battery and coil device 45. Compartment 43 is a cable compartment. From the connectors carrying conductors |2 to An associated gas pump 50,

48 of the latter run the cables the spark plugs o. run from engine E,

conduit for the con-- has an inlet and an outlet 52 connected to discharge respectively into compartments 42 and 43. A connection 53 leads from compartment 43 to compartment 41. Both compartments 4| and 42 vent to the atmosphere, while the compartment 43 discharges through a connection !9 into a manifold s, as in the former case, so as to pass the fluid dielectric from the pump 50 to the compartments 4l, 42, and 43, and thence to the harness.

While the fluid dielectric referred to above is air, other insulating gases, such as nitrogen, carbon dioxide, and the like, may be employed.`

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it isintended that all matter contained in the above description or shown inthe accompanying drawings shall be interpreted as illustrative and not ina limiting sense.

Having describedmy invention, what I claim 4 as new and desire to secure by Letters Patent is:

stator provided with windings in one compart-' ment, a breaker and distributor mechanism in a second compartment; and conductor cables for ignition purposes in 'a third compartnent, a pump for supplying air under pressure to said compartments and harness, and driving means for said rotor and pump. V

3. A magneto-electric machine, comprising, in combination, a casing therefor having a plurality .of enclosing compartments, a rotor and a stator provided with windings in one compartment, a breaker and distributor mechanism in a second compartment, and conductor cables for ignition purposes in athird compartment, an associated pump for supplying air under pressure, a 'conduit leading the air discharged by said pump into* said rotor-containing compartment, and conduits leading from said rotor-containing compartment with one leading to said breaker-containing compartment and another leading to said cables-containing compartment.

4. In an ignition system for airplane engines and the like, the combination comprising an engine having spark plugs, a source of high tension E. M, F. having a substantially closed casing formed with compartments and a functioning unit Component thereof in each of said compartments, encased harness leading from a. compart-- ment of said casing to said engine spark plugs, and means for supplying fluid dielectric under pressure to said casing compartments and encased harness in succession.

5. In an' ignition system for ai'plane` engines and the like, the combination comprising an engine having spark plugs, a source of high tension E., M. F. having a substantially closed casing formed with compartments and a functioning unit Component thereof in each of said Compartments, a pump for supplying air under pressure, encased harness leading from a compartment of said source of high tension E. M. F. to said engine 'spari: plugs, and means for conveying the air discharged by said pump in succession to said compartments and to said harness.

6. In an ignition system for airplane engines and the like, the combination comprising an engine having spark plugs, a magneto having a substantially closed casing formed with Compartments and a functioning unit Component thereof `in each of said compartments, an associated ing means for coupling the same to be driven by said engine at half engine speed, a pump for supplying and maintaining air at desired pressure driven from said coupling, and encased harness leading from said magneto for supplying said high tension current to each of said spark plugs; said pump, said casing and said encased harness being arranged for the passage of air at desired' pressure therethrough successively in the order named. i

8. In an ignition system for airplane engines and the like, the combination comprising a multi-cylindered engine having spark plugs for each cylinder, a single magneto-electric machine having a casing, a pump for supplying and maintaining air at desired pressure, means in common with saidpump and said magneto-electric machine for driving the same. from said engine, harness connected to said casing comprising a plurality of high tension current conducting cables each leadingiron said magneto-elcctric machine to one of said engine spark plugs, each of said cables having a fiexible substantally airtight metal sheath in spaced relation thereto and provided with terminal air-bleeding means, and conduit connections between said pump and magneto-electric machine whereby the supercharging air passes from said pump, through at least the portion of said casing to which said.

harness is attached and thence through said sheaths in parallel, finally bleeding to the atmosphere.

9. In an ignition system for airplane engines and the like, the combination comprising a mu1- ti-cylindered engine having spark plugs for each cylinder, a single source of high tension E. M. F. having a casing provided with separate Compartments, a functioning unit Component of said source of high tension E. M. F. in each of said c-ompartments, encased harness leacng from one of said compartments to said spark plugs, common means for supplying fluid dielectric under pressure to said encased harness and the compartment from which it leads, and means for separately supplying fluid dielectric under pressure to at least one other of said compartments which contains a sparking functioning unit.

10. A magneto-electric machine, comprising, in combinati'on, a casing therefor having a plurality of enclosing compartments, a rotor and a stator provided with windings in one'compartment, a breaker and a distributor mechanism in a second compartment, conductor cables for ignition purposes in a third. compartment, an encased ignition harness including portions of at chine to one of said engine spark least some of said cables leading from said third compartment, means for supplying fluid dielectrio' under pressure, a conduit leading fluid dielectric supplied by said means into said retorcontaining compartment, a passage leading from said rotor-containing compartment to said breaker-containing compartment, and another passage leading from said rotor-containing compartment to' said cable-containing compartment.

11.- A magneto-electric machine, comprising, in combination, a casing therefor, a partition in said casing defining with a portion thereof a flrst compartment, a second partition in said casing defining with the remaining portion thereof second and third compartments, a rotor and stator provided with windings in the first compartment, breaker and distributor mechanism in the second compartment, conductor cables forignition purposes in the third compartment, means for supplying fluid dielectric under pressure, a conduit leading fluid dielectric supplied by said means into said rotor-containing compartment,

said first mentioned partition being provided with" a passage for leading fluid dielectric from said rotor-containing compartment to said breakerpressure, meanshaving a passage leading the fluid dielectric supplied by said first-mentioned means into said windings-containing compartment, means having a passage leading from the latter compartment to the cables-containing compartment provided for passage of fluid dielectric under pressure therebetween and serving with the third compartment as a passage for a conductor cable from the secondary winding to the distributor mechanism, and means having a passage leading from the windings-containing compartment to the breaker-containing compartment to provide for passage of fluid dielectric from the former to the latter, said breaker-com taining compartment being provided with fluidbleeding means. a

14. In an ignition system for airplane engines and the like, the combination comprising amulti-cylindered engine having spark plugs for each containing compartment, and a conduit leading from said rotor-containing compartmentto aid cable-containing compartment, said breakercontaining compartment being provided with means for bleeding fluid to permit controlled escape thereof to the atmosphere.

12. In an ignition system for airplane engines and the like, the combination comprising a multi-cylindered engine having spark plugs for each cylinder, a magneto-electric machine having a casing therefor, a partition in said casing defining with a portion thereof a first compartment, a second partition in said casng defining with the remaining portion thereof second and third compartments, a rotor and stator provided with windings in the first compartment, breaker and distributor mechanism in the second compartment, conductor 'cables for ignition purposes in the third compartment, means for supplying fluid dielectric under nected to said third compartment comprising a plurality of high tension current conducting cables each leading from said magneto-electric maplugs, each of said cables having a substantially fluid-tight metal 'sheath in spaced relation thereto provided with terminal fluid-bleeding means, a Conduit leading the fluid'dielectric supplied by said firstmentioned means into said rotor-containing compartment, said first-mentioned partition being provided with a passage for leading fluid dielectric from said rotor-containing compartment to pressure, a harness con-` said breaker-containing compartment, and a ,V

conduit leading from said rotor-containing compartment to said cable-containing compartment, said breaker-containing compartment being provided with fluid-bleeding means t'o Permit controlled escape of fluid to the atmosphere.

' 13. In an ignition system for airplane engines and the like, the combination comprising a casing having a plurality of enclosing compartments, a set of windings in one compartment including a primary adapted to carry low tension current and a secondary adapted to supply high tension current, a breaker and distributo; mechanism in the second compartment, said breaker being adapted periodically to interrupt flow of low tension current in the primary, conductor 'cables for ignition purposes in a third compartment, means for 'supplying fluid dielect'ric under cylinder, a casing having a plurality of enclosing compartments, a set of windings in one compartment including a primary adapted to carry low tension current and a secondary adapted to supply high tension current, a breaker and distributor mechanism in a second compartment, said breaker being adapted periodically to interrupt flow of low tension current in the primary, conductor cables for ignition purposes in a third compartment, means for supplying fluid dielectric under pressure, a harness connected to said third compartment comprising a plurality of high tension current conducting-.cable's each leading from said magneto-electric machine to one of said engine spark plugs, each of said cables having a substantially fluid-tight 'metal sheath in spaced relation terminal fluid-bleeding means, a. Conduit leading the fluid dielectric supplied by said means into said windings-containing compartment, a Conduit leading from the latter compartment to the cables-containing compartment provided for passage of fluid dielectric under pressure therebetween and serving with the third compartment as a passage for a conductor' cable from the secondary winding to distributor mechanism, and

means having a passage leading from the windings-containing compartment to the breakercontaining compartment to rovide for passage of fluid dielectric from the former to the latter. said breaker-containing compartment being provided with fluid-bleeding means.

15. In an ignition system for airplane engines and a secondary adapted to supply hi h -gases therebetween a breaker and distributor mechanism in the second compartment, conductor cables for ignition purposes in the third compartment in conducting relation to said distributor mechanism including terminals in mountings on said partition, means for supplying fluid dielectric under pressure, a Conduit leading the fluid dielectric supplied by said means into said windings-containing compartment, and a conduit leading from the latter compartment to the cables-containing compartment providing for passage of fluid dielectric under pressure therebetween and serving with the third compartment as a passage for a conductor cable from one of the windings to the distributcr mechanism, said thereto provided with a primary adapted to carry low tension current, ,a partition in'a portion oi' said an atinospe'e of'fluid dielectric under press'ure' windings containing and breaker containing compartments being connected together by a passage permitting fluid dielectric under pressure to be forced from the tormer to the latter, said with fluid-bleedng means.

16. In a distributing mechanism tor high tension masnetos the combination comprising a casing' member adapted to be divided into a. chamber for housing supply and distributins cables in w 'breaker-containing compartxnent being provided 5 distributing member in the other cha'mber.

i LLOYD H. SCO'IT. 

